#include <iostream>
using namespace std;

#define F(X,Y)   (X)--; (Y)++ (X)*(Y);
struct A{
	int a;
	char b;
	char c; 
};
 char *mystrstr(const char *src, const char *des)
{
	if (*src=='\0')
	{
		if (*des=='\0')
		{
			return (char*)src;
		}
		else
		{
			return (char*)NULL;
		}
	}
	while(*src!='\0')
	{
		int n=0;
		while(*(src+n)==*(des+n))
		{
			if (*(des+n+1)=='\0')
			{
				return (char *)src;
			}
           n++;
		}
		src++;
	}

	return NULL;

}
int main()
{
	//cout<<sizeof(A)<<endl;		
	char str[]="123434xyz";
	char* str1=mystrstr(str,"34x");
	cout<<str1<<endl;
}